The ornamental design for a flatwareholder, as shown and described.
FIG. 1 is a perspective view of my new design, a flatware holder, illustration of a user's arm and flatware are shown in broken lines to illustrate the environment of the claimed design and forms no part thereof.
FIG. 2 is an end view of the flatware holding end of the flatware holder shown in FIG. 1.
FIG. 3 is a side view of the flatware holder.
FIG. 4 is an end view of the receiving end of the user's hand and extending arm of the flatware holder; and,
FIG. 5 is a side view looking into the end illustrated in FIG. 4.